Tow bar apparatus

ABSTRACT

A truck-mounted towing crane is constructed with a tubular boom pivoted at one end and raised by a power cylinder. A tow bar assembly is pivotally mounted to the other end of the boom so that the former may be folded back to a storage position and the boom lowered for storage of the crane in a small space. The tow bar assembly includes a downward and rearward extension for the boom and a cross-bar supported from below at its center by a ball joint connected to the free end of the boom extension.

United States Patent j 1191 Aquila 1 March 6, 1973 1 TOW BAR APPARATUS2,145,378 1/1939 Trippensee ..2l4/86 A x 2,436,000 2/1948 Fleming..214/86 A [76] Inventor: Joseph Aquila, 144-41 231st Street, 92 8 V 214ale NY. "422 3,522,8 /l970 egors /86 A l [22] Filed: Nov. 9, 1970Primary Examiner-Albert J. Makay & S ff 1 pp NO: 87,863 AttorneyOstrolenk, Faber Gerb 0 en [57] ABSTRACT A truck-mounted towing crane isconstructed with a tubular boom pivoted at one end and raised by a powercylinder. A tow bar assembly is pivotally mounted to the other end ofthe boom so that the former may be folded back to a storage position andthe boom lowered for storage of the crane in a small space. The tow barassembly includes a downward and rearward extension for the boom and across-bar supported from below at its center by a ball joint connectedto the free end of the boom extension.

8 Claims, 7 Drawing Figures TOW BAR APPARATUS This invention relates tocranes in general, and more particularly relates to a truck-mountedcrane for towing disabled automobiles.

F or the most part, prior art truck-mounted cranes for the towing ofautomobiles included a boom that is raised and lowered by cablesextending over a tall gantry. Driving power for the cables was usuallysupplied by a mechanical connection to the automobile engine and thehorizontal tow bar was usually suspended from the free end of the boomby chains or cables.

Prior art cranes of this type have proven to be ineffective when mountedon relatively light duty, so-called pickup, trucks and called upon totow relatively heavy automobiles, such as Cadillacs and Lincolns. Forthe most part, difficulties arise because of weight distribution, whichon one hand impedes lifting of the automobile, and on the other handmakes the towing vehicle top-heavy, so that there is a great danger ofturnover.

These prior art constructions are also disadvantageous in that once thecrane structure is mounted on the truck, the bulkiness of the cranestructure essentially precludes the truck from being used for anypurpose bu't towing.

In order to overcome the foregoing objectionable features of prior artconstructions, the instant invention provides a relatively compact cranestructure, which when not being used for towing may be readily collapsedto permit the tow truck to be used for other purposes. In particular,the device of the instant invention comprises a relatively smallhorizontal base adapted to seat on the floor of a pickup truck body andbe bolted or otherwise secured directly to the truck frame.

A tubular boom is pivoted at one end thereof to the base, and is raisedand lowered by a hydraulic operated power cylinder, driven by a fluidpump operated by an electric motor. A tow bar assembly is pivotallymounted on the other end of the boom, so as to be movable between astorage and an operating position. In the storage position the tow barassembly is folded back so as to overlie the boom and be close to thebase.

The tow bar assembly includes a boom extension which, in the operatingposition of the tow bar assembly extends downwardand to the rear of theboom. The cross-bar of the tow bar assembly is supported from below by aball joint connected to the free end of the boom extension.

Accordingly, a primary object of the instant invention is to provide anovel construction for a crane having a tow bar means.

Another object is to provide a crane construction of this type whichpermits collapse to a relatively compact form when not being used;

Still another object is to provide a tow bar assembly in which thecross-bar is supported from below by a swivel on a boom extension.

A further object is to provide a tow bar assembly in which a ball jointprovides for limited universal motion of the cross-bar relative to theboom.

A still further object is to provide a crane construction which makesextensive use of relatively lightweight tubular members.

These objects, as well as other objects of this invention, will becomereadily apparent after reading the following description of theaccompanying drawings, in which:

FIG. 1 is a perspective showing a crane, constructed in accordance withthe instant invention, mounted on the bed of a relatively lightweightpickup truck, with the tow bar assembly folded back to a storageposition.

FIG. 2 is a fragmentary view of the elements of FIG. 2, with the tow barassembly in its operating position.

FIG. 3 is a side elevation of the crane elements of FIG. 2.

FIG. 4 is a plan view of the elements of FIG. 3.

FIG. 5 is a cutaway fragmentary view of the ball joint forming elements5-5, looking in the direction of arrows 55 of FIG. 4.

FIG. 6 is a side elevation of the safety device which limits accidentaldownward movement of the boom.

FIG. 7 is a fragmentary longitudinal cross-section of the main elementsof FIG. 6.

Now referring tov the FIGS. Crane 10, constructed in accordance withteachings of the instant invention, is intended to rest upon bed 11 of arelatively light duty vehicle or so-called pickup l2 and be secured tothe frame thereof by bolts or other suitable means (not shown).

Crane 10 includes horizontal base 15, constructed of spaced side members16, 17 connected by transverse members 18, 19. Members 16, 17 aretubular and of square cross-section as at A in FIG. 4, and cross members18, 19 are also tubular but of circular cross-section, being illustratedat C and D, respectively, in FIG. 4. Boom 20 is a unitary tubular memberof square cross-section having a hump therein. Reinforcing strip 21 iswelded to the upper surface of boom 20 and extends for substantially theentire length thereof. The front end of boom 20 is secured to circulartube 22 at the center thereof, and extends at right angles thereto.Transverse frame member 19 is substantially equal in length to tube 22,being disposed therein and cooperating therewith to form the main pivotfor boom 20. Triangular stabilizing plates 23, 24 extend from oppositesides of boom 20, being secured to tube 22 and acting to stabilize boom20 against movement outside of a plane perpendicular to base 15.

l-Iydraulically operated power cylinder 25 is pivotally connected at 26to radial extension of transverse frame member 18. Piston rod 28extending from the other end of cylinder 25, is pivoted at its free end29 to downward extension 31 of boom 20 at a point located to the rear oftransverse frame member 18. When boom 20 is in its lowermost position,power cylinder 25 extends substantially parallel to base 15 and boom 20is positioned only slightly thereabove as in FIG. 1.

The rear end of boom 20 is provided with spaced upwardly extendingtrunion forming elements 32, 33 supporting pin 36 to which tow barassembly 40 is pivotally mounted. Assembly 40 includes boom extension 41and cross-bar 42. Boom extension 41 is of the same cross-section as boom20, and cross bar 42 is a tubular member of circular cross-section.Spaced trunion forming elements 34, 35, secured to opposite side of boomextension 41 at the front thereof, are disposed adjacent to the outersurfaces of elements 32, 33, and are connected to pivot pin 36. In theoperating position of crane 10, the engaged angled abutting edges ofboom extension 41 and boom 20 position boom extension 41 on an inclineextending downwardly and to the rear of boom 20. v

Modified U-shaped bracket 50 is welded to the rear end of boom extension41, and includes generally horizontal leg 51, forming a support for seat52 upon which swivel joint ball 53 is mounted. Stud 54, extendingdownward from ball 53 through seat member 52 and bracket arm 51, isengaged by nut 55 to secure ball 53 to bracket 50. Lock washer 56 isinterposed between nut 55 and bracket leg 51. Socket forming elements61, 62 are secured to cross bar 42 at the center thereof, and lock crossbar 42 to ball 53. Elements 61, 62 cooperate to form a spherical socketwherein ball 53 is disposed, to constitute a swivel joint which, for themost part, supports cross bar 42 from below.

Each of the hooks 57 welded at the ends of cross-bar 42, supports achain 58 having an automobile engaging hook 59 secured to the lower endthereof. Safety chain 61 extends between horseshoes 62, 63, secured tocrossl-bar 42 and boom extension 41, respectively. Chain 61 is longenough to permit cross-bar 42 to swivel as required. Yet there is verylittle slack in chain 61a, so that in the unlikely event that swiveljoint 53, 61, 62 breaks, cross-bar 42 remains mechanically connected toboom extension 41 to prevent separation of the towed vehicle (not shown)from the towing vehicle 12.

Rod 28 of power cylinder 25 is extended to raise the rear end of boom bymeans of fluid pumped into power cylinder by fluid pump 66 operated bybattery powered motor 67. Manually operated control 68 is biased to aneutral position, and is selectively operable to two other positions. Inone of these positions, motor 67 is energized so that pressure is builtup within power cylinder by fluid pump 66 to extend rod 28 and raise therear end of boom 20. In the other position of control 68, fluid ispermitted to escape from power cylinder 25, to the reservoir portion ofpump 66, at a controlled rate to gradually lower the rear end of boom20.

Safety device 70 permits boom 20 to be raised freely, but in the absenceof safety control 71 being pulled outward to releasing position,downward movement of boom 20 will be automatically stopped after verylimited movement. That is, control 71 is at one end of cable 76 in stiffflexible cover 77. The other end of cable 76 is connected at its otherend to locking pin 72, the latter being slidably disposed withintransverse tubular guide extension 73 of tube 74 having rod 75 enteredinto the upper end thereof. The lower end of tube 74 is pivotallyconnected at 88 to a radial extension at the center of transverse basemember 18.

The upper end of rod 75 is pivotally connected to a downward extensionof boom 20, located forward of pivot 88 and forward of bend line 91 inboom 20. Tension spring 78 is disposed outside of guide extension 73,being connected to tab 79 projecting from extension 73, and to tab 81 atone end of pin 72, thereby biasing pin 72 toward tube 74 or towardlatching position. Radial extension 82 from pin 72 cooperates withIongitudinal slot 83 in extension 73 to prevent rotation of pin 72.

Rod 75 is provided with aligned longitudinally spaced locking notches84, 84, etc., positioned to receive the free end of locking pin 72. Asseen in FIG. 7, the left end of notch 84 is substantially parallel tothe axis of extension 73, thereby being transverse to the axis of rod75. The right end of notch 84 is at a substantial incline with respectto the axes of both elements 73 and 75. Thus, with pin 72 in its lockingposition shown in FIG. 7, movement of rod to the right with respect totube 74 is blocked. However, rod 75 is free to be withdrawn from tube74, with the right-hand boundary of notch 84 acting as a cam surface toengage the rounded tip of locking pin 72 and force the latter out ofnotch 84.

Operation of the apparatus hereinbefore described proceeds as follows.Crane 10 is usually transported in its storage or collapsed position,shown in FIG. 1, wherein tow bar assembly 40 is folded forward aboutpivot pin 36 to a position wherein boom extension 41 overlies boom 20and cross-bar 42 rests against the upper surface of bar 21 on boom 20.Piston rod 28 is retracted, and the rear end of boom 20 is in itslowered position adjacent to pickup bed 1 1.

When pickup 12 arrives at the vicinity of the vehicle to be towed, towbar assembly 40 is pivoted to the rear about pin 36, to its operatingposition wherein crossbar 42 is to the rear of pickup 12 and isinitially below bed 11. Hooks 59 are brought into engagement with thevehicle to be towed, and chains 58 slipped into hooks 57. Control 68 isoperated to energize motor 67, thereby. driving fluid pump 66 andextending cylinder rod 28 to lift the rear end of boom 20 and tow barassembly 40 attached thereto, thereby raising the vehicle to be towed.Motor 67 is deenergized when boom 20 is generally at the desired towingheight. Thereafter, control 68 is operated to exhaust fluid from powercylinder 25 back to the reservoir section of pump 66, with the downwardmovement of boom 20 being arrested through the cooperation of locking 72and one of the notches 84. If boom 20 is too low at this time, powercylinder 25 is operated again to raise boom 20 until locking pin 22falls into an appropriate one of the notches 84, which will hold boom 20in a required towing position.

When the towed vehicle arrives at its destination, safety lock releasecontrol 71 is pulled outward, thereby retracting pin 72 beyond theperiphery of rod 75, and control 68 is operated to release fluid frompower cylinder 25 and permit lowering of boom 20 until hooks 59disengage the towed vehicle.

Although not illustrated in detail in the FIGS. or hereinbeforedescribed, it is noted that for the most part the connections betweenelements subject to major mechanical stresses are made by welding. Forexamples, socket forming elements 61, 62 are welded to cross-bar 42;member 51 and elements 34, 35 are welded to boom extension 41; elements32, 33, bar 21 and plates 23, 24 are welded to boom 20; plates 23, 24are also welded to tube 22; transverse frame or base members 18, 19 arewelded to longitudinal frame members 16, 17; and there are welds alongbend line 91.

Although in the foregoing there have been described preferredembodiments of this novel invention, many variations and modificationswill now become apparent to those skilled in the art, and it ispreferred therefore that the instant invention be limited not by thedisclosure contained herein but only by the appending claims.

The embodiments of the invention in which an exclusive privilege orproperty is claimed are defined as follows.

l. A crane including an elongated boom; a main pivot at the front end ofsaid boom; a power operated device connected to said boom from below forraising the rear end thereof; a tow bar assembly including an elongatedboom extension and an elongated cross-bar; said boom extension connectedatone end thereof to said rear end of said boom to be raised by saidpower operated device as the latter raises said boom; with said tow barassembly in a working position said boom extension havingitsother endpositioned below and to the rear of said one end; swivel meansconnecting said cross-bar at its mid-region to said other end of saidboom extension and generally at right angles with respect thereto; agenerally horizontal base including spaced elongated side membersextending generally parallel to the plane of movement for said boom;said main pivot being positioned at the front of said base; said basealso including a transverse member positioned rearward of said mainpivot; said power operated device connected between said transversemember and a point on said boom positioned to the rear of saidtransverse member; said cross-bar being positionable below said base;stabilizing members extending from opposite sides of said boom andconnected to said base at the front thereof.

2. A crane as set forth in claim 1, in which said swivel means comprisesa device supporting said cross-bar from a point therebelow.

3. A crane as set forth in claim 1', in which said boom,

said boom extension, and said cross-bar are each constructed of tubularelements.

4. A crane as set forth in claim 1 also including a safety deviceconnected to said boom to limit lowering thereof in the event there is amalfunction of the power operated device.

5. A crane as set forth in claim 4 in which the safety device comprisesfirst and second telescoping elements, one connected to said boom andthe other connected to said base, a retractable locking member carriedby one of said elements and biased to be engageably by lockingformations of the other of said elements as said boom is being lowered,thereby limiting lowering movement of said boom unless said lockingmember is retracted.

6. A crane as set forth in claim 1 in which the power operated devicecomprises fluid cylinder means.

7. A crane including an elongated boom; a main pivot at the front end ofsaid boom; a power operated device connectedto saidboom from below andcomprising the sole means for raising said boom and elements secured tothe rear end of said boom for raising the rear end thereof; a tow barassembly including an elongated boom extension and an elongatedcross-bar; said boom extension connected at one end thereof to said rearend of said boom to be raised by said power operated device as thelatter raises said boom; with said tow bar assembly in a workingposition said boom ex tension having its other end positioned below andto the rear of said one end; swivel means connecting said cross-bar atits mid-region to said other end of said boom extension and generally atright angles with respect thereto; a pivot means connecting said one endof said boom extension directly to said rear end of said boom, saidpivot means and said main pivot being parallel to each other andgenerally parallel to said cross-bar; said tow bar assembly beingmovable about said pivot means as a center to a storage position,

wherein said boom extension overlies said boom, with said other end ofsaid boom extension being forward of said rear end of said boom, andwith both said boom and said boom extension being lowered to generallyhorizontal positions; a generally horizontal base including spacedelongated side members extending generally parallel to the plane ofmovement for said boom; said main pivot being positioned at the front ofsaid base; said base also including a transverse member positionedrearward of said main pivot; said power operated device connectedbetween. said transverse member and a point on said boom positioned tothe rear of said transverse member; said cross-bar being positionablebelow said base.

8. A crane as set forth in claim 7 also including stabilizing membersextending from opposite sides of said boom and connected to said base atthe front thereof.

1. A crane including an elongated boom; a main pivot at the front end ofsaid boom; a power operated device connected to said boom from below forraising the rear end thereof; a tow bar assembly including an elongatedboom extension and an elongated cross-bar; said boom extension connectedat one end thereof to said rear end of said boom to be raised by saidpower operated device as the latter raises said boom; with said tow barassembly in a working position said boom extension having its other endpositioned below and to the rear of said one end; swivel meansconnecting said cross-bar at its mid-region to said other end of saidboom extension and generally at right angles with respect thereto; agenerally horizontal base including spaced elongated side membersextending generally parallel to the plane of movement for said boom;said main pivot being positioned at the front of said base; said basealso including a transverse member positioned rearward of said mainpivot; said power operated device connected between said transversemember and a point on said boom positioned to the rear of saidtransverse member; said cross-bar being positionable below said base;stabilizing members extending from opposite sides of said boom andconnected to said base at the front thereof.
 1. A crane including anelongated boom; a main pivot at the front end of said boom; a poweroperated device connected to said boom from below for raising the rearend thereof; a tow bar assembly including an elongated boom extensionand an elongated cross-bar; said boom extension connected at one endthereof to said rear end of said boom to be raised by said poweroperated device as the latter raises said boom; with said tow barassembly in a working position said boom extension having its other endpositioned below and to the rear of said one end; swivel meansconnecting said cross-bar at its mid-region to said other end of saidboom extension and generally at right angles with respect thereto; agenerally horizontal base including spaced elongated side membersextending generally parallel to the plane of movement for said boom;said main pivot being positioned at the front of said base; said basealso including a transverse member positioned rearward of said mainpivot; said power operated device connected between said transversemember and a point on said boom positioned to the rear of saidtransverse member; said cross-bar being positionable below said base;stabilizing members extending from opposite sides of said boom andconnected to said base at the front thereof.
 2. A crane as set forth inclaim 1, in which said swivel means comprises a device supporting saidcross-bar from a point therebelow.
 3. A crane as set forth in claim 1,in which said boom, said boom extension, and said cross-bar are eachconstructed of tubular elements.
 4. A crane as set forth in claim 1 alsoincluding a safety device connected to said boom tO limit loweringthereof in the event there is a malfunction of the power operateddevice.
 5. A crane as set forth in claim 4 in which the safety devicecomprises first and second telescoping elements, one connected to saidboom and the other connected to said base, a retractable locking membercarried by one of said elements and biased to be engageably by lockingformations of the other of said elements as said boom is being lowered,thereby limiting lowering movement of said boom unless said lockingmember is retracted.
 6. A crane as set forth in claim 1 in which thepower operated device comprises fluid cylinder means.
 7. A craneincluding an elongated boom; a main pivot at the front end of said boom;a power operated device connected to said boom from below and comprisingthe sole means for raising said boom and elements secured to the rearend of said boom for raising the rear end thereof; a tow bar assemblyincluding an elongated boom extension and an elongated cross-bar; saidboom extension connected at one end thereof to said rear end of saidboom to be raised by said power operated device as the latter raisessaid boom; with said tow bar assembly in a working position said boomextension having its other end positioned below and to the rear of saidone end; swivel means connecting said cross-bar at its mid-region tosaid other end of said boom extension and generally at right angles withrespect thereto; a pivot means connecting said one end of said boomextension directly to said rear end of said boom, said pivot means andsaid main pivot being parallel to each other and generally parallel tosaid cross-bar; said tow bar assembly being movable about said pivotmeans as a center to a storage position, wherein said boom extensionoverlies said boom, with said other end of said boom extension beingforward of said rear end of said boom, and with both said boom and saidboom extension being lowered to generally horizontal positions; agenerally horizontal base including spaced elongated side membersextending generally parallel to the plane of movement for said boom;said main pivot being positioned at the front of said base; said basealso including a transverse member positioned rearward of said mainpivot; said power operated device connected between said transversemember and a point on said boom positioned to the rear of saidtransverse member; said cross-bar being positionable below said base.